Xerographic plate made by cast coating



*a eum r n-m Feb. 12, 1963 V. V. JONES XEROGRAPHIC PLATE MADE BY CASTCOATING Filed ma 14, 1959 INVENTOR. VIRON V. JONES BY (M A, SW MQM A 7'TOR/VE Y United States Patent Ufitice 3,9713% Patented Feb. 12, 1953 3077 393 XERGGRAPHI C PLAli MADE BY (JAST COATHNG Viron V. Jones, MortonGrove, llL, assignor to Bell 3: Howell Qonipany, hicago, llll., acorporation of Illinois Filed May 1 5-, 1959. Ser. No. 813,242 2 Claims.(Cl. 96-1) This invention relates to an improved xerographic materialand in particular to an improved xer-ographic plate, paper or film. Morespecifically this invention relates to a xerographic plate, paper orfilm including a finely divided photoresponsive pigment in an insulatingresin, and to methods and apparatus for employing the material inxerography.

Xerography in its new commercial aspects is a method for making copiesof original documents whereby a specially prepared paper or plate ischarged in the dark with static electricity by means of positive ornegative discharge, as is disclosed for example in Carlson U.S.2,588,699. The charged material is then exposed to a master copy bycontact or projection, or an electrostatic image is formed by othersuitable means, and the image is developed by applying an electroscopicmaterial such as an electro-statically charged powder. The resultingreproduction is an image corresponding to the electrostatic image andmay be a positive or negative image depending on various electrostaticimage parameters. In the usual case the developing powder may be aresinous material and may be fixed or made permanent by application ofheat or a suitable solvent.

Now in accordance with the present invention a new and usefulxerographic member is formed by coating a two-phase photoconductiveinsulating layer onto a highly specular surface and subsequentlyseparating the photoconductor layer from said surface to produce a newphotoconductive member having a special and superior recording surface.Cptionally, the photoconductor layer may be mechanically supported onthe side opposite to this special surface by means of a support backingsuch as paper, plastic, a metal foil or the like. In any event the newxerographic member is adapted for xerographic processing according toknown methods such as for example the methods of Carlson US. 2,297,691.

't is therefore an object of the present invention to provide a newxerographic member and in particular to provide a new xerographicrecording member having a superior recording surface.

It is an additional object of the invention to provide a new xerographicrecording member capable of reproducing electric and visible records inextremely fine detail and in high resolution.

It is another object of the invention to provide a new xerographicrecording member particularly adapted for microfilm recording.

It is an additional object of the invention to provide new methods,apparatus, and materials for the production and use of xerographicrecording members.

It is another object of the invention to provide new and improvedXerographic apparatus, methods, and materials.

Additional objects of the invention will in part be obvious and will inpart become apparent from the following specification and drawing inwhich:

FIG. 1 is a diagrammatic View of a portion of a xerographic memberaccording to one embodiment of this invention;

FIG. 2 is an enlarged diagrammatic view of a xerographic memberaccording to a second embodiment of the invention;

FIG. 3 is a representation of coating apparatus for the preparation of anew xerographic member.

Present commercial pigment-binder type materials available for thereproduction of original documents by means of xerography include suchmaterials as a layer of a zinc oxide pigment in a silicone resin binder.Such materials are generally produced by coating the pigmentbindercomposition Onto a paper base in a suitable organic solvent mixture andthereafter drying the composition in air. When evaluated from thestandpoint of a micro image recording these materials are inadequateand, in particular, the pigment binder type of material is generally oflimited resolution in that the resolution limit is generally in theorder of 60 to 90 lines per mm. For microrecording, a resolution in thisorder enables a reduction ratio of about 10 to 1 from an originaldocument and this resolution limitation thereby prohibits the use ofsuch materials in modern reproduction systems requiring a reductionratio as great as 40 to 1.

Previously no attention has been paid to the surface requirement of thephotoconductive material. Microscopic examination of the surface ofplates prepared by means of Middleton, U.S. 2,663,636, or other pigmentbinder xerographic materials, discloses a rough contour which is not inkeeping with a surface from which it is expected to reproduce theultimate in fine line microcopies. Plates and papers prepared by usingpigments such as zinc oxide in a suitable binder as the photoconductorand without special regard to the manner of preparation generalireproduce a resolution of 60 to lines per mm. from an original document,and when surface improvements have been made as directed in the presentinvention, a resolution at least as high as 280 lines per turn. can beachieved, depending to some degree upon the particular formulations usedand the methods used for development.

Middleton US. 2,663,636 and certain other systems employ a coating of axerographic pigment binder or two phase photoconductor on a conductingsurface such as metal or a humectiiied paper in such a manner that afterevaporating the solvent, the photoconductive material adheres tightly tothe support. The present invention involves the preparation and use ofthe Xerographic composition and coating process in such a manner as toencourage a condition of non-adherence between the photoconductor andits backing support. Specifically, the

present invention includes coating a specially prepared photoconductorcomposition on a smooth, highly polished surface of such material asglass, aluminum, stainless steel, chromium, mylar, or other smoothsurfaces, the choice of material being such that after evaporation ofthe solvent, the two layers, i.e., the photoconductive material and thesupport, represent an incompatible nonadhering sandwich which can bereadily separated. The surface of the free photoconductive material orfilm which originally faced the polished surface of the casting supportduring drying will be an exact replica of that surface, while theopposite or air dried surface is rough and behaves as conventionalbinder type photoconductive mate rials having a resolution limit of 60to 80 lines per mm. The specially prepared or replica surface on theother hand is capable of resolving up to at least 280 lines per mm.according to present data.

FIG. 1 is a diagrammatic view of a self-supporting xerographic recordingmember according to one embodiment of the present invention. Thexerographic rnernber generally designated it) comprises a uniformtwophase composition including solid particulate or pigment particles 11suspended and bound together by means of a continuous phase binder 12.One surface of the pigment binder composition is comparatively irregularin configuration as illustrated by surface 14 whereas the oppositesurface illustrated by surface 13 is essentially smooth and uniform, andis capable of specular reflection and otherwise characterized by thehighest possible degree of surface uniformity. Microscopic examinationof the photoconductive layer by reflected illumination discloses thatthe cast or replica surface 15 is extremely smooth and correlatesperfectly with exceedingly high resolution capabilities. It is presentlyunderstood that at least a portion of the improvement in resolution isimproved by elimination of hills and valleys from the surface asillustrated by the difference in surface configuration between surface14 and surface 15 and in addition by elimination of non-uniformdistribution of the photoconductive particles in said surface 15. Thus,in addition to the undesirable hills and valleys, the air-dried freesurface has localized areas which are either excessively rich in ordeficient in the resin material, creating heterogeneous areas of about 1to 50 microns in diameter to interfere with resolution requirements formicroimages. It is presently believed and understood that the pigmentsized particles contained in the solvent-pigmentbinder system alignthemselves uniformly along the contact surface on which the mixture isspread and that this geometrically uniform alignment is substantiallyindependent of gravitational direction upon application. In other wordsthis uniform alignment results regardless of whether the pigmentcomposition is allowed to settle on a horizontal surface or is coated ona surface maintained in a position other than horizontal.

In preparation of xerographic plates, papers, and films, according tothe present invention there may be employed a wide variety ofphotoactive pigments dispersed in and bound together by suitableinsulating binders. Thus, there may be employed, for example, theselenium pigment of Middleton US. 2,663,636 as well as the other pigmentbinder compositions disclosed therein. There may also be employed nowconventional zinc oxide-binder compositions such as are disclosed inPhotographic Engineering, Phosphor-Type Photoconductive Coatings forContinuous Tone Electrostatic Electrophotography, Eugene Wainer (vol. 3,No. 1, pp. 1222, 1952), and in 'RCA Review, Electrofax DirectElectrophotographic Printing on Paper, C. J. Young and H. G. Greig(December 1954, pp. 469-484), and the other compositions disclosedtherein. In general, suitable pigments include, but are not limited to,organic and inorganic phosphor type materials including those namedabove and various photoconductive oxides, sulfides, selenides,tungstates and the like such as, for example: zinc oxide, zinc sulfide,zincmagnesium oxide, cadmium sulfide, zinc silicate, cadmium selenide,mercuric iodide, mercury oxide, mercuric sulfide, indium trisulfide,arsenic-sulfide, arsenic selenide, antimony trisulfide, lead oxide, andthe like.

It has been found by continued experimentation that a photoconductiveinsulating film or layer made by conventional methods can be improvedaccording to methods and techniques disclosed in the present invention.Thus, for example, the working procedures of the following examples maybe modified by the substitution of other photoactive materials to attaincomparable improvements in products. lllustratively, any of thephotoresponsive pigments listed above may be employed for xerographicrecording materials and can be improved according to the processes andtechniques of the present invention to produce high resolutionxerographic recording materials specifically useful for micro-recording.For the purpose of illustration, however, the examples are limited toconventional zinc oxide pigment such as generally employed in commercialxerographic papers.

Similarly, a wide variety of resin binder materials may be employed. Ingeneral, care must be taken to select chemically compatiblepigment-binder compositions and to blend such compositions inproportions and concentr'ations such as to produce optimum responses toactivating illumination and optimum insulating characteristics in theabsence of such activating radiation. Such techniques and controls are,of course, well known in the art.

In the following examples a conventional zinc oxide pigment, employed incommercial xerographic paper, is used iliustratively with severalinsulating binder compositions to prepare self-supporting and supportedxerographic recording layers.

xample 1 Zinc oxide (Florence Green Seal No. 8) grams 150 Acetone (techgrade or better) ml 400 Resin (Bakelite VYNS, a polyvinyl chlorideacetate resin) grams 50 These constituents were combined in a WaringBlendor and mixed until smooth. This xerographic composition was coatedwith a common doctor blade technique, set for 10 mils, upon a glass orchrome surface which had previously been thoroughly cleaned. Afterdrying in air, the coating was peeled off and further cured in aphotographic print dryer set for a temperature of 65 C. for 30 minutes.Either side of this material when charged in the dark with a negativecorona of 3,000 volts or more and exposed to a photographic positiveimage in a typical printing box was capable of developing good blackimages with a conventional magnetic brush using a resin toner-magneticiron carrier system. However, in order to demonstrate the bestresolution of which the material is capable, a magnetic brush of thetype disclosed in Young US. 2,786,439 was used with a developmentmixture consisting of ten micron iron powder and three micron ironpowder in a ratio of about one to one. With this mixture the fine irondevelops out in the unexposed areas yielding an iron powder positive.With this developing system and the xerographic material just described,resolution as high as 140 lines per mm. is possible on the smoothsurface. On the rough or air dried surface only 60 to lines waspossible.

These developed images can be fixed by spraying carefully with afixative or commercial aerosol containing a clear plastic solution, orcan be protected for illustrative purposes by overlaying with Scotchtape.

Example 2 Zinc oxide (Florence Green Seal No. 8) grams 150 Siliconesolution (GE. SR82, a silicone resin available from General ElectricCompany) ml. Acetoneto adjust viscosity.

The silicone solution was first evaporated to a thick viscous syrup,then all constituents were combined in a Waring Blendor and mixed untilsmooth. Coatings were made upon mylar film with a doctor blade set for10 mils, then dried at room temperature. The resulting sandwich wascured in an oven at 200 F. for 30 minutes. These coatings were somewhatfragile and were fastened to gummed paper or gummed aluminum foil formechanical support. The mylar casting surface was then peeled away fromthe photoconductor. When freshly prepared this surface was capable ofreproducing consistently a resolution greater than 200 lines per mm,and, usually, a resolution up to 280 lines per mm. with the irondeveloping system described in Example 1. The rough or air dried surfacewas not capable of resolving more than 60 to 80 lines per mm.

Example 3 Zinc oxide (Florence Green Seal No. 8) grams Piccoflex(Pennsylvania Industrial Chemical Company) grams 60 Toluene ml 25Acetone ml 100 The Piccoflex resin was previously soaked in the 25 ml.toluene, then combined with the remainder of the constituents in aWaring Blendor, and mixed until smooth. The resulting emulsion wascoated on mylar film by means of a doctor blade set for 10 mils, driedat room omes-a Example 4 Zinc oxide (Florence Green Seal No. 8) grams150 Methanol ml 40f) Bakelite XYSG (a polyvinyl butyral resin) grams 75These constituents were combined in a Waring Blendor and mixed untilsmooth. Coating was carried out as in Example 1 upon glass. After dryingin air the material was peeled oif and further cured in a photographicprint dryer for 30 minutes at 65 C. Upon the smooth surface it waspossible to resolve 140 lines per millimeter. Upon the rough or airdried surface it was only possible to resolve 60 to 80 lines.

Example Zinc oxide (Kadox No. 25) grarns 150 Acetone ml. 400 BakeliteVYNS "grams" 70 These constituents were combined in a Waring Blendor andmixed until smooth. Coating was carried out as in Example 1. Afterdrying in air at room temperature, the material was peeled off andfurther cured in a photographic print dryer for 30 minutes at 65 C. Uponthe smooth side of this material it was possible to resolve reproducibly280 lines per mm. with the iron developing mixture described inExample 1. Upon the air dried or rough surface the best resolution was100 to 140 lines.

In the preceding example there are prepared flexible unsupportedphotoconductive films from various binder compositions, which films aresuitable for use in xerographic processing provided adequate care istaken to prevent rough handlin with resulting mechanical damage.

In general, however, it has been found that the self-supporting films dorequire careful handling when employed in manual laboratory operations,or when employed in high speed xerographic equipment in which the filmis subjected to unusual stresses. In many instances, however, themechanical properties of the film may be substantially improved by meansof mechanical support bases against which the films are lying during theprocessing steps. In accordance with one embodiment of the presentinvention, increased mechanical strength can be added to the film itselfwith at least no impairment of xerographic processing and preferablywith alfirmative improvement in processing by applying a suitablesupport base to the film prior to drying and prior to removal from thecasting surface. When the support base is paper, the supported layer isa preferred embodiment as a recording medium for documentaryreproduction. According to one procedure the photoconductive insulatingfilm can be supported on an overlay of the same or a different film froma resin binder applied with a lower concentration of photoactive pigmentor preferably with substantially no such pigment. This overlay of theresin binder causes an electrically insulating backing surface to beplaced behind the xerographic recording member and adds sufiicientstrength to the photoconductor to permit its use in ordinary Xerographicequipment and processes. If desired, additives such as, for example,electrically conductive materials, may be incorporated into the overlayresin.

In FIG. 2 is illustrated such a xerographic film, generally designated16, having a support film or web 17 overlying an air dried surface 18 ofa photoconductor 6 layer such as illustratedin FIG. 1. The cast surface19 of the film is smooth and highly uniform.

Example 6 The xerographic composition of Example 1 was coated on a glassplate after drying, but before stripping, an overcoat consisting of 50grams of XYSG (a polyvinyl butyral resin available from BakeliteCorporation) and 400 ml. of methanol was applied by a simple coatingdevice such as a doctor blade to such a depth that the overcoat whendried was from 0.5 to 1.0 mils in thickness. This material when dried,stripped from the glass plate, and cured in the manner previouslydescribed was found to be a satisfactory xerographic material andsufficiently strong for mechanical use. Similar supported plates wereformed by the same procedure using the following overcoating materialsapplied in an appropriate solvent: carboxyl methyl cellulose, Methocel,vinyl chloride, vinyl chloride-acetate, vinyl acetate, cellulose acetateand cellulose-acetate-butyrate. In some cases it is desirable toincorporate a conventional plasticizer in the overcoat to impartflexibility as well as improve strength, but in all cases a mechanicallystrong xerographic member is formed with or without the plasticizer.

In FIG. 3, is illustrated, diagrammatically, apparatus adapted to applya paper or other web backing support to the photoconductive insulatingfilm according to the present invention. In this apparatus a suitablecasting surface, such as for example a cylinder it} is positioned toreceive a photoconductive insulating pigmenbbinder composition 21 from asuitable source such as a hopper 22. If desired a smoothing device suchas a doctor blade 24 may be employed to produce a uniform layer of thephotoconductor. A paper supply roll 25 is positioned to feed a Web ofpaper 26 to the exposed surface of the photoconductive insulating layer,preferably passing around pressure roll 27 which is adapted to press theweb firmly against the photoconductive insulating layer. Positioned at asubsequent point around the surface of the cylinder 20 is a take-offroller 28 around which the paper web may be peeled from the cylinder,carrying with it the now dried photoconductive insulating layer.

Example 7 A strong supported photoconductor is produced on the apparatusof FIG. 3 by depositing a layer of thin porous paper immediately afterthe emulsion coating knife 24 in such a manner as to form an intimatelybound sandwich, a tough paper layer on top and the cast emulsionunderneath. The binder-pigment composition of Example l was used and thepaper overlay was a tough but porous material such as Gaylord Kraft25-#, or a comparably suitable mechanically strong paper support. Afterthe material had dried, the sandwich Was stripped from the castingsurface and cured in the manner as previously described. Satisfactoryimages. have been developed on this material, and it was foundsufiiciently strong for a mechanized process.

The prior art pigment-binder photoconductors such as, specifically,paper supported zinc oxide-resin binder materials are generally intendedfor single use applications. Thus for example it is usual to form anelectrostatic image on such papers and then to develop and fix the imagedirectly on the paper. When such papers have been employed for imagetransfer followed by reuse, it has been found that generally a secondand certainly a third of a series of copies is seriously degraded inpicture quality apparently because of retention of residualelectrostatic developer powder on the surface. In the following Examples8 and 9 are illustrated preparations of pigment binder xerographic papermaterials which have been employed for the production of at leastconsecutive developed and transferred images without noticeableimpairment of image quality.

7 Example 8 Zinc oxide (Florence Green Seal #8) grams 150 Methylenechloride ml 75 Silicone resin (GE. SR82) ml 2 Epoxy resin (Araldite 502,Ciba Corp.) grams 75 These constituents were combined in a WaringBlendor and mixed until smooth. This pigment-binder mixture was measuredout into smaller convenient batches before hardening. For each 30' gramsof mixture 1 or 2 grams of catalyst HB951 (Ciba Corp.) was added, whichwas then quickly coated on mylar film with a doctor blade set for 6mils. After drying for a short time in a warm area to remove the highlyvolatile methylene chloride, the coatings were then cured in an oven at250 F. or higher for to minutes to harden. Quickly after removal fromthe oven, the coatings were fastened to a gummed aluminum plate or otherfirm support with the pigment-binder surface contacting the adhesive.The mylar casting film was peeled away revealing a smooth hard surfaceupon which it was possible to develop electrostaticimages withconventional LectroX positive toner (Haloid Xerox Inc., Rochester, NewYork). Such images could be transferred to a paper support byelectrostatic means and fixed in the usual manner. The plates could thenbe cleaned with cotton or flannel cloth and used over again. After amultitude of such cyclings, the surface of the photoconductor remainedclean and uninjured. This surface is capable of developing images withresolution as high as 140 lines after 100 cycles of development andtransfer, enabling the process to be used either for direct copy usingresin type developing powders or high reduction with special developingsystems.

Example 9 Zinc oxide (Kadox #25) grams 150 Methylene chloride ml 100Silicone resin (G.E. SR82) .ml 2 Epoxy resin (Araldite 502, Ciba Corp.)grams 75 These constituents were combined in a Waring Blender and mixeduntil smooth. The resulting blend was utilized in 30 gram portions towhich 1 or 2 grams of catalyst HN9'51 (Ciba Corp.) was added. Aftermixing, the composition was coated in mylar film with a doctor blade setfor 6 mils. The coatings were allowed to dry for a short time in a warmplace to remove the highly volatile methylene chloride, then cured in anoven to harden at a temperature of 250 F. or higher for 5 to 10 minutes.The coatings were removed from the oven and while still hot quicklyfastened to a gummed aluminum plate or other firm support with thepigment-binder layer contacting the adhesive. The mylar casting film waspeeled off revealing a smooth hard surface upon which it was possible todevelop electrostatic images with the conventional LectroX positivetoner (Haloid Xerox Inc., Rochester, New York). Such images can betransferred to a paper support by electrostatic means and fixed in theusual manner. The plates can be cleaned with cotton or flannel cloth, orwith a rotating brush as shown in US 2,832,977, and used over again.After a multitude of such cyclings, the surface of the photoconductorremained cleaned and uninjured. This surface is capable of developingimages with resolution as high as 280 lines per mm, enabling the processto be used either for direct copy using resin type developing powders orvery high reduction with special developing systems.

zinc oxide as the photoresponsive pigment and Bakelite VYNS as theinsulating resin binder and employing in each example, one of fivesensitizing dyes: rose bengal, methylene blue, fluorescein, acridineorange and eosin yellow. Based on the solids in the layer, 0.01% byweight of the dye was added to the mixture of pigment and resin. Theresulting photoconductor layer in each case was characterized by asmooth, fine resolution cast surface and by an improved range ofspectral response to visible light. In general the photographicresolution was substantially better than the resolution of conventionalprior art pigment-binder compositions. In particular, resolutions up toabout lines per mm. can beobtained with fine particle size pigments andsensitizing dyes. -The smooth cast surface can be prepared as aself-supporting film, or preferably as a layer supported on a paper orother backing 'by the procedures of Examples 6, 7, or 8.

The new xerographic recording member according to the present inventionis characterized by a'smooth, shiny, spectral refiective surface, by theability to accept .an adequate electrostatic charge generally in theorder of several hundred volts negative polarity, and the ability todissipate this charge selectively in response to a pattern ofillumination to produce a high quality xerographic latent image. Theimage, when developed, is of high resolution equal to a resolution of upto 280 'lines per millimeter, and greater than the resolution of .aconven tionally prepared, calendered surface. The new plate 'issufliciently strong in unsupported condition for careful use inxerographic processes and inparticular the paper supported recordingmember of the present invention is fully compatible with either manualor automatic achine operations of xerography. The new plate is capableof repeated reuse without apparent deterioration throughout a multitudeof xerographic cycles including xerographic deposition of developermaterial and cleaning of residual developer material. Thecharacteristics 'of the new xerographic plate or member are particularlyuseful in microrecording where it is desiredto record original materialin a size reduced by about 40 diameters for subsequent enlargement backto the original size, andin fine quality full sized prints whereresolution and quality of appearance are significant.

What is claimed is:

1. The method of recording 'xerographic images, said method having aresolution capability in excess of 10,0 lines per mm., comprisingforming a liquid dispersion of photoconductive zinc oxide particles in asolvent solution of a resin, coating said dispersion in a uniform layeronto a specular and non-adhering surface, thereafter and prior to dryingsaid coating layer adhering to the outer surface layer of said coatinglayer opposite to said surface layer on said specular surface a papersupport layer, hardening said resin in contact with said specularsurface and said paper support layer by evaporating said solvent fromsaid layer adhering to said paper support layer to form a hardened resincoating layer, separating said coating layer adhering to said papersupport layer from said specular surface, said coating layer having saidphotoconductive particles dispersed therethrough and having a singlespecularly smooth electrostatically developable working surface alongwhich said particles are oriented to form a region of higher and moreuniform particle density than the remainder of said coating layer,depositing a uniform electrostatic charge onto said working surfacecreating a sensitive xerographic plate, exposing said surface to apattern of light and shadow to form an electrostatic latent imagethereon conforming in configuration to said light and shadow pattern,and electrostatically developing said electrostatic latent image on saidworking surface.

2. A method of preparation of a new xerographic recording membercomprising forming a liquid dispersion of photocon-ductive zinc oxideparticles in a solvent solution of a resin, coating said dispersion in auniform layer onto a specular and non-adhering surface, thereafter priorto drying said coating layer adhering to the outer surface layer of saidcoating layer opposite to said surface layer on said specular surface apaper support layer, hardening said resin in contact with said specularsurface and said paper support layer by evaporating said solvent fromsaid coating layer to form a hardened resin layer adhering to said papersupport layer, and separating said coating layer adhering to said papersupport layer from said specular surface, said coating layer having saidphotoconductive particles dispersed therethrough and having a singlespecularly smooth electrostatically developable working surface alongwhich said particles are oriented to form a region of higher and moreuniform particle density than the remainder of said coating layer.

References Cited in the file of this patent UNITED STATES PATENTS1,719,166 Bradner July 2, 1929 10 2,221,019 Clarke Nov. 12, 19402,588,569 Picard Mar. 11, 1952 2,739,243 Sheldon Mar. 20, 1956 2,799,609Dalton July 16, 1957 2,860,048 Deubner NOV. 11, 1958 FOREIGN PATENTS201,416 Australia Apr. 13, 1956 OTHER REFERENCES Metcalfe et al.:Journal of the Oil and Colour Chemists Association, vol. 39, No. 11,pages 845-856 (1956).

1. THE METHOD OF RECORDING XEROGRAPHIC IMAGES, SAID METHOD HAVING ARESOLUTION CAPABILITY IN EXCESS OF 100 LINES PER MM., COMPRISING FORMINGA LIQUID DISPERSION OF PHOTOCONDUCTIVE ZINC OXIDE PARTICLES IN A SOLVENTSOLUTION OF A RESIN, COATING SAID DISPERSION IN A UNIFORM LAYER ONTO ASPECULAR AND NON-ADHERING SURFACE, THEREAFTER AND PRIOR TO DRYING SAIDCOATING LAYER ADHERING TO THE OUTER SURFACE LAYER OF SAID COATNG LAYEROPPOSITE TO SAID SURFACE LAYER ON SAID SPECULAR SURFACE A PAPER SUPPORTLAYER, HARDENING SAID RESIN IN CONTACT WITH SAID SPECULAR SURFACE ANDSAID PAPER SUPPORT LAYER BY EVAPORATING SAID SOLVENT FROM SAID LAYERADHERING TO SAID PAPER SUPPORT LAYER TO FORM A HARDENED RESIN COATINGLAYER, SEPARATING SAID COATING LAYER ADHERING TO SAID PAPER SUPPORTLAYER FROM SAID SPECULAR SURFACE, SAID COATING LAYER HAVING SAIDPHOTOCONDUCTIVE PARTICLES DISPERSED THERETHROUGH AND HAVING A SINGLESPECULARLY SMOOTH ELECTROSTATICALLY DEVELOPABLE WORKING SURFACE ALONGWHICH SAID PARTICLES ARE ORIENTED TO FORM A REGION OF HIGHER AND MOREUNIFORM PARTICLE DENSITY THAN THE REMAINDER OF SAID COATING LAYER,DEPOSITING A UNIFORM ELECTROSTATIC CHARGE ONTO SAID WORKING SURFACECREATING A SENSITIVE XEROGRAPHIC PLATE, EXPOSING SAID SURFACE TO APATTERN OF LIGHT AND SHADOW TO FORM AN ELECTROSTATIC LATENT IMAGETHEREON CONFORMING IN CONFIGURATION TO SAID LIGHT AND SHADOW PATTERN,AND ELECTROSTATICALLY DEVELOPING SAID ELECTROSTATIC LATENT IMAGE ON SAIDWORKING SURFACE.